JPS6343062A - Low-noise gear - Google Patents

Abstract

PURPOSE:To obtain a low-noise gear having a high strength at a gear teeth portion and a boss portion which gear is strong and does not generate discomfort noise, by making a sintered density of a disc portion of the gear lower than that of the other portions. CONSTITUTION:A low-noise gear 1 is formed by sintering in such a manner that a sintered density of a disc portion 3 is made low, and a sintered density of a gear teeth portion 4 and a boss portion 2 formed at opposite ends of the disc portion 3 is made high. Accordingly, a mechanical strength of the gear teeth portion 4 and the boss portion 2 both having a high sintered density is greatly increased. Further, a vibrational noise propagated from the gear teeth portion 4 having a high sintered density may be effectively damped at the disc portion 3 having a low sintered density. As a result, the low-noise gear 1 is made strong and does not generate discomfort noise or the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the improvement of sintered gears, and particularly to damping the propagation of vibrations generated in the meshing portion of the gears, thereby reducing the noise of the gears during operation. This invention relates to a low-noise gear designed to reduce noise.

[Prior art and its problems]

Most of the conventionally known gears are generally gears constructed with a focus on mechanical strength, and the shearing gears are made of solid hard metal, and the entire upper part is made of the same material and is integral. Because of this structure, the vibrations generated in the meshing portion during operation are propagated as they are without being damped by the disk portion, and are emitted to the outside as very loud noise.

Therefore, in order to improve the above-mentioned disadvantages, relatively soft metal is used as the main material, and in order to strengthen the engaging part consisting of grooves, notches, etc., hard metal different from the disk part is fitted into the grooves or notches, or The development of fitted gears has also been achieved. In such a gear, the meshing part and the disc part are made of different materials, so vibrations generated in the meshing part during operation are attenuated in the process of propagating from the meshing part to the disc part, reducing noise. Although it is possible to reduce
On the contrary, there was a problem in that the mechanical strength of the meshing portion had to be reduced.

In addition, synthetic resin gears, which have recently become popular for light-duty use, are molded by injection molding, so they are easier to manufacture than gears molded from solid metal. , and the vibration that occurs during operation in the meshing part can be said to be less compared to gears made of solid metal, but since the molding material itself is made of synthetic resin, the strength of the meshing part can be significantly increased. cannot increase.

In addition, in order to improve the mechanical strength of the above-mentioned synthetic resin gears, there have been several attempts to improve the mechanical strength of the gears by mixing glass fiber etc. into the synthetic resin to increase the rigidity of the resin. All of these have conflicting problems in terms of strength and noise.

[Means and effects for solving the problems] The present invention has been made in view of the above-mentioned circumstances, and in a sintered gear, the sintering density of the disk portion is adjusted between the vicinity including the meshing portion and the shaft insertion portion. By configuring the structure to have a lower density than the neighboring sintered density, the strength of the meshing part of the gear and the shaft insertion part is maintained at high strength, and the vibrations that occur in the meshing part during operation are effectively damped. The purpose of the present invention is to provide a low-noise gear that achieves this.

[Example] A low-noise gear according to the present invention is to be obtained by employing sintering (powder metallurgy) technology.

Sintering technology heats an aggregate of metal powders such as iron, or metal powders pressure-molded into an appropriate shape, at a predetermined temperature to bring the powders into close contact with each other, thereby producing the desired gears, sprockets, etc. It can be said that this is a well-known technology that is convenient for obtaining processed products such as ratchets and cams.

However, in the processing of various products manufactured to date, for example, in the sintering of gears, most of them have adopted sintering technology with a focus only on strengthening the mechanical strength of the meshing part. Sintering technology is used because the material has a high melting point, is a special material, that is, a porous body, or a composite material of metal and non-metal.

The present invention utilizes sintering technology to effectively damp vibrations (so-called noise) generated in the meshing parts of gears during operation.

An embodiment of the low-noise gear according to the present invention will be described in detail below with reference to FIGS. 1, ta+ and fbl, and FIG. 2.

The graph shown in Figure 1 ia) shows the sintered density -
The graph (in the figure), which represents the relationship between the vibration sound attenuation rate, represents the relationship between the sintered density and mechanical strength of the same material.

That is, according to the graph in the above figure (al), the attenuation rate of the vibration noise of sintered iron (for example, the vibration noise generated at the meshing part of a gear) shows a fairly high attenuation rate when the sintered density is low. It can be seen that as the sintered density increases, the attenuation rate gradually decreases.On the other hand, according to the graph in Figure □□□), the mechanical strength of the sintered iron is weak when the sintered density is low. However, it can be seen that it gradually becomes stronger as the sintered density increases.

The low-noise gear according to the present invention was created by focusing on the sintered density, vibration sound damping, and mechanical strength properties of the above-mentioned sintered iron, and its specific configuration is as shown in Fig. 2. be.

In the figure, 1 is a low-noise gear sintered and formed to have a two-phase structure using the sintering technology described above, and 2 is a low-noise gear in the center of the gear with high density (the density ρ in this high-density region is approximately ρ). <
668, but in this example, the density ρ=6
, 8)), 3 has a low density on its outer periphery (the density ρ in this low density region is approximately ρ〉6.
In this example, the density ρ=6.5.
The disc part 4 is formed by sintering at a high density on the outermost periphery of the low-noise gear (the density ρ in this high-density area may be approximately within the range of ρ<6.8, but in this example Here, the meshing portion is sintered and formed with the same density ρ-6, 8 as in the shaft insertion portion 2 described above.

In the low-noise gear 1 having the above structure, the disk portion 3 has a low density, and the meshing portion 4 and the shaft insertion portion 2 located on both sides of the disk portion 3 are sintered and formed to have a high density. The mechanical strength of the meshing part 4 and the shaft insertion part 2, which are both high-density sintered parts, is significantly strengthened, and the disc part 3, which is made of low-density sintering, has a high-density sintered mesh. It is possible to effectively attenuate the vibration sound (noise) generated in the section 4 and propagated.

Furthermore, in the above embodiments, gears were used as examples of sintered molded products. Products such as sprockets that are preferably removed can also be sintered and formed, so the present invention is not limited to the above examples.

〔Effect of the invention〕

As explained above, in a sintered gear composed of a meshing part, a disc part, and a shaft insertion part, the sintered density of the disc part is lower than that of other constituent parts. Because of this structure, the strength of the meshing part of the gear and the shaft insertion part can be maintained at a high level, and the vibrations that occur in the meshing part during operation are effectively damped by the disc part, so it is robust and durable. It is possible to provide a low-noise gear that does not emit unpleasant noise.

[Brief explanation of drawings]

Figure 1 fat is a graph showing the relationship between sintered density and vibration sound attenuation rate when metal powder is sintered.
2 is a graph showing the relationship between sintered density and mechanical strength of the same material as above, and FIG. 2 is a sectional view showing an embodiment of the low noise gear according to the present invention. DESCRIPTION OF SYMBOLS 1...Low-noise gear, 2...Shaft insertion part, 3...Disc part, 4...Meshing part. Patent applicant: Honda Motor Co., Ltd. Figure 1 (0) (BL Figure 2 Procedures: 1 copy of the main text) October 6, 1985 Patent Application No. 184799 2, Title of the Invention Low Noise Gear 3, Relationship with the Amendment Case Patent Applicant Address 2-101-1 Minami Aoyama, Minato-ku, Tokyo Name (532)
) Honda Motor Co., Ltd. 4, Agent 101 Address 2-7-4 Kanda Tsukasa-cho, Chiyoda-ku, Tokyo (Detailed Description of the Invention Column 6 in 11 Specification, Contents of Amendment (1) Specification No. 5 3rd row from the bottom [ρ<6.8 J
(2) Correct “ρ>6.5 j” in the first line of page 6 of the specification to “ρ>6.8 J.”
Correct it to 〈6.5.''

Claims (1)

[Claims] A sintered gear composed of a meshing part, a disc part, and a shaft insertion part, characterized in that the sintered density of the disc part is lower than that of other constituent parts. Low noise gear.